Classification of the Diseases
Disease is nothing but a deviation from a normal physical, physiological, and mental state of affairs. The classification of diseases in animals is based on various parameters, and it is explained in this post in more detail.
Disease
Disease is made up of two words: dis (not) and ease (comfort). It indicates the inability of a person or animal to perform normal physiological functions if nutrition and environmental factors are maintained at an optimal level.
Disease is classified based on a lot of parameters; these are described below–
- According to mode of origin or genesis
- Based on system involved
- According to changes in the organ
- According to specific cause
- According to The mode of infection
- According To clinical manifestation (intensity)
- Based on the spread of the disease
- According to the place of origin
- According to the deficiency
- According to the physiological turnover
1. According to mode of origin or genesis
Hereditary or genetic disease
In Hereditary or genetic disease, genome is responsible for the disease. These are transmitted by either sire or dam to the offspring because of genetic predisposition.
Example of Hereditary or genetic diseases are-
- Haemophilia
- Diabetes mellitus
- Colour blindness
- Epilepsy
- Broken wind in horse (tracheal ring defect)
Congenital disease
Congenital diseases are acquired during the intra uterine life. These occur during organogenesis. Examples are-
- Atresia ani
- Cleft palate
- Congenital brucellosis
- Tuberculosis
Acquired disease
Acquired diseases are acquired after birth. these are contracted during entire life span of the animal. Examples are-
- Senile cataract
- Acquired hydrocephalus
2. Based on system involved
Localized disease
Clinical changes attributable to a disease is prominent and confined to a particular spot or organ. Examples are glossitis, abscess, stomatitis etc.
Generalized disease
Whole system is involved; all parts of body may be involved. Examples are toxemia, septicemia etc.
3. According to changes in the organ
Structural or organic disease
Structural / organic disease is the disease which brings about pathological changes in the structure of any organ. e.g.; pericarditis, nephritis, rickets, osteomalacia etc.
Functional disease
Functional disease is the diseases which affects functional efficacy of any organ without altering structural component of it. Eg; idiopathic epilepsy, arrhythmia etc.
4. According to specific cause
Specific diseases are the diseases which have got definite identity and are produced by specific pathogen or factor-
- Contagious
- Infectious
Contagious disease
Contagion– pollution by touching. Here the disease spread by intimate contact with the diseased animal. Examples are RP, FMD, fungal infections etc.
Infectious disease
Infecire– to put into. Disease is caused by living infecting organism. Examples are viral disease, bacterial disease, parasitic & mycotic disease etc.
5. According to the mode of infection
Primary disease (principal disease)
Primary disease (principal disease) indicates those diseases which originates independently and are not influenced by another disease. Examples are canine distemper, rabies, milk fever, ketosis etc.
Secondary disease
Secondary disease indicates those diseases which supervene out of already prevailing primary disease.
Superimposed secondary bacterial diseases are very common outcome of primary viral diseases. Secondary pneumonia is very common after viral diseases. Examples are kennel cough due to B. bronchoseptica is a complication seen in canine distemper, Secondary ketosis seen in abomasal displacement and TRP etc.
Intercurrent disease
This occurs as a sequale to primary disease. Examples are Chorea, a neurological complication of canine distemper, where there is continuous twitching of some group of animals, Panting (panters)- especially in exotic and cross breed cows after FMD, Hypertrichosis is the overgrowth of hairs and hoof is noticed in FMD recovered Animals.
6. According To clinical manifestation (intensity)
Peracute
Duration of the disease is shorter than acute with a very severe course. Illness lasts for few hours to 48 hours. e.g. peracute mastitis, peracute HS, Anthrax etc.
Acute
Acute type of disease is characterised by a sudden onset and comparatively short course with severe manifestations. Generally illness prevails for 3-14 days.. e.g. FMD, RP, Anthrax etc.
Subacute
Onset and severity is lesser than acute one. Usually it has a course of 2-4 weeks. Example is sub acute mastitis.
Chronic
Chronic disease which has got a protracted course. Though the disease is not severe in character but the long run may terminate fatally. Illness over 4 weeks is considered as chronic disease. Examples are TB, para TB, Brucellosis etc.
7. Based on the spread of the disease
Sporadic diseases
Sporadic diseases which affects a single animal and shows no tendency to spread within the herd. Eg ; sporadic bovine encephalomyelitis.
Enzootic diseases
Enzootic disease denotes an outbreak of disease among animals in a definite area or particular district. Eg; enzootic haematuria in cattle, anthrax.
Epizootic diseases
Epizootic diseases which affects a large population of animals in large areas. Eg ; RP, FMD.
Endemic diseases
Endemic diseases which is normally maintained in animals is called endemic diseases.
Panzootic diseases
When epidemic reaches on unusually large size in some country or spreads over many countries, then is is called Panzootic disease.. Eg ; influenza.
8. According to the place of origin
Indigenous disease
Disease which are prevalent as native one is called Indigenous disease. Examples are TB, filariosis etc.
Exotic diseases
Diseases which have been acquired from foreign countries is called Exotic diseases. Example is African horse sickness.
Emerging disease
Disease which are not in existence but may be introduced at any time is called Emerging disease. Examples are louping ill in sheep, bird flu etc.
9. According to the deficiency
Classification of the Diseases based on the deficiency-
- Deficiency diseases – such as hypovitaminosis
- Nutritional disease – such as hypocalcemia
10. According to the physiological turnover
Classification of the Diseases based on the physiological turnover–
- Metabolic diseases – Such as milk fever, hypomagnesemic tetany etc.
- Production diseases – Such as fatty cow syndrome
- Endocrine diseases – Such as dibetes mellitus